1. Field of the Invention
The present invention relates to a motor, and more particularly to a stator of a motor in which the height of each tooth's tip is lower than the height of a rotor and the height of a yoke is higher than the teeth's tip so that costs for manufacturing a motor is decreased and the efficiency of the motor is increased.
2. Description of the Related Art
Generally, a motor generates a driving force by which a rotor is driven by electromagnetic interaction between a stator and the rotor.
FIGS. 1 and 2 are views illustrating the stator of a conventional motor.
A stator 10 of a motor, as shown in FIGS. 1 and 2, includes a ring-shaped yoke 12 disposed at the outside of a rotor 20, a plurality of teeth 16 protruding from the inner wall of the yoke 12 toward the rotor 20 in the radial direction, forming slots 14 therebetween to have a desired shape, and being spaced apart from each other, and coils 18 wound around the teeth 16 and electrically connected to an external electric power.
The stator 10 constructed as described above is described as follows.
First, stator sheets 10′ having planar shapes of the yoke 12 and the teeth 16 are manufactured from a very thin electrical steel sheet in the blanking process (See FIGS. 2a and 2b). Next, the stator sheets 10′ are laminated so as to have a predetermined height and a desired shape 10″, and the coils 18 are wound around the laminated stator sheet 10″, so that a stator 10 is completed.
Here, as shown in FIG. 2a, the remainder of the electrical steel sheet 30 out which the stator sheets 10′ are cut, namely, a scrap 30′ is of use and is disposed of.
Hereinafter, since the basic structure of the conventional stator is similar to the stator shown in FIGS. 1 and 2, the detailed description and drawings thereof may be omitted.
Though not depicted in the accompanying drawings, the conventional stator may have the yoke and teeth integrated with each other by the iron powder metallurgy method.
Otherwise, as shown in FIG. 3, a stator 40 may be manufactured such that a yoke 42 is cut out from an electrical steel sheet and teeth 44 are manufactured by the iron powder metallurgy method.
According to the stator manufactured by the conventional process, if all conditions except for the stator 10 in FIGS. 1 and 2 and the manufacturing method are same, manufacturing costs can be reduced by manufacturing some parts using the iron powder metallurgy method in comparison to the stator 10 in FIGS. 1 and 2. However, since the magnetic characteristics of the iron powder is not better than that of the electrical steel sheet, the efficiency of a motor including the conventional stator in FIG. 3 becomes remarkably worse than that of a motor including the stator 10 in FIGS. 1 and 2.
Meanwhile, according the conventional manufacturing method as shown in FIG. 3, since the stator 40 is manufactured such that the heights of the yoke 42 and the teeth 44 are lower than the height of a rotor 40′, effective magnetic fluxes passing through the teeth 44 are increased by the over-hang effect so that the efficiency of a motor can be enhanced.
However, if the stator 40 is manufactured by the iron powder metallurgy method, since the height of the stator 40 is lower than the height of the rotor 40′ in order to obtain the overhang effect, it is difficult to increase the efficiency of a motor because of a large amount of the increased core loss of the yoke 42.